1. Field of the Invention
The present invention relates generally to an identification system and, more specifically, to an identification system and method for identifying a turbine engine with a numeric identity that is readable by a remote device connectible in electrical communication with an identification module attached to the turbine engine.
2. Description of the Prior Art
Many different types of systems have been developed to store a numeric value in such a way that the numeric identity can be determined by an external circuit that is connected in electrical communication with a module that is used to retain the stored identification value.
U.S. Pat. No. 3,560,941, which issued to Wallace on Feb. 2, 1971 discloses a circuit board that is used in the memory unit of a repertory dialer. The circuit board is provided with ten columns of electrically connected sockets with each column provided with a resistor that is weighted in resistive value according to the column in which it is located. Each of these columns is used to represent a digit value in an address. Ten rows are also provided and correspond to the digit positions in an address. In order to program the circuit board, a wire lead is connected from the socket in each row to a socket in the column corresponding to the digit value. This permits the programming of information directly in analog form on the board. The memory, comprising a plurality of such boards, stores three dimensional information in a two dimensional matrix. The weighted resistors provide the third dimensional information.
U.S. Pat. No. 3,863,231, which issued to Taylor on Jan. 28, 1975, discloses a read only memory with a plurality of annular fuse links. The memory device is provided with a set of input conductors that are disposed at right angles to a set of output conductors with each input conductor connected to each output conductor by a respective resistive fusible link. In operation, information is written into the memory device by passing currents that are large enough to fuse the selected links. All of the fusible links have resistance and dimensions such that they are not fused by application of a voltage of a predetermined magnitude but are fused by application of a voltage of twice that predetermined magnitude.
U.S. Pat. No. 4,344,064, which issued to Bitler et al on Aug. 10, 1982, describes a circuit package and a method of marking the circuit package in an identifiable manner. The circuit package typically includes thin film components of a circuit. The circuits on the package typically undergo tests and adjustment operations prior to final bonding of a chip to the circuit. A first value of an element marks the article as belonging to a first group of articles having first circuit characteristics. The initial value of the element is selectively altered to a second value upon a determination that the article has circuit characteristics other than those of the first group. In the preferred embodiment, the first group is a group of electrically acceptable articles while other characteristics are those of defective articles. The mark is typically altered by a current of sufficient magnitude to burn portions of the element or by selective application of radiant energy such as a laser beam.
U.S. Pat. No. 4,484,213, which issued to Franklin on Nov. 20, 1984, describes a binary weighted resistor package. This device provides a circuit which is variably configured to provide a plurality Of individual resistance magnitudes. It comprises a plurality of series connected devices attached to a lead frame with a parallel circuit connected to each of the devices that can control the bypass or use of all or some of the connected devices. A plurality of series connected resistors, for example, are selected to have resistance magnitudes that relate to the other resistors by powers of two. By selectively breaking fusible links, the total series resistance of the resulting circuit can be tailored to any one of a plurality of magnitudes.
U.S. Pat. No. 3,441,804, which issued Klemmer on Apr. 29, 1969, describes a thin film resistor which includes a basic resistor intercoupled with a network of selectively intercoupled individual trimming resistors which add or subtract selected increments of resistance to that of the basic resistor. The minimum value trimming resistor provides a predetermined impedance while each other trimming resistor provides an impedance equal to a different power of two of that predetermined impedance. The trimming resistors may be connected in series or in parallel.
An article, by R. B. Wahler, appeared in the IBM Technical Disclosure Bulletin Volume 20 No. 6 in November 1977 which was entitled "Using Fusible Links to Apply Machine-Readable Serial Numbers to Printed-Circuit Boards". That article discloses the use of a series of parallel fusible links for the purpose of providing a group of binary ones or zeros which can be used as a serial number on a printed circuit board. This device does not utilize resistors or means for determining the resistance of an identification circuit. Instead, it provides a plurality of yes/no signals on parallel lines which can be read by automatic equipment.
U.S. Pat. No. 4,016,483, which issued to Rudin on Apr. 5, 1977, discloses a microminiature integrated circuit that includes weighted elements and contactless switching means for fixing the impedance at a preselected value. This circuit impedance device comprises a plurality of impedance elements formed on a substrate with each element having an impedance, a first input terminal, an output terminal and a plurality of electrically permanently alterable contactless switching elements. Each electrically permanently alterable contactless switching element comprises fusible conductive links or shortable diodes. In the preferred embodiment of this device, it comprises resistive elements fabricated with thin film or monolithic integrated circuit technology and serves as a variable resistor or as a variable voltage divider that performs the function of a fixable contactless trimming potentiometer.
U.S. Pat. No. 4,884,070, which issued to Hannaford on Nov. 28, 1989, discloses a method and apparatus for multiplexing switch signals. This device provides a single conductor for transmitting a signal which conveys information relating to the state of a plurality of switches which may be simultaneously or individually actuated from one position to another. It disposes a plurality of resistors in series between two points of differing voltage potential and places a switch in parallel with each of the resistors. In addition, the resistors are selected to have magnitudes that relate to each other by powers of two. By monitoring the voltage at a preselected point in the circuit, the number of switches that are actuated can be determined by determining the effective resistance of the hand held device containing the switches.
While the above described patents each relate generally to methods and devices which store identification information or permit the user to selectively determine a resistance of a component, none of the patents provide a means by which a device can be identified with a module that is relatively inexpensive and in which an identification number can be easily selected. In addition, the patents described above do not provide a device that can remotely read the identification number stored in the module with a relatively high degree of accuracy while using relatively few and inexpensive components to store the identification number in the module.